Abstract: A method for performing a physical activity management system includes producing a first exercise solution for a user by a calculating unit, wherein the first exercise solution includes a first target of an exercise intensity of the user; detecting a physical signal of the user in a period of time by a sensing unit, wherein the physical signal includes a heart rate and a respiratory frequency; producing an exercise status of the user by the calculating unit according to the physical signal detected by the sensing unit, wherein the exercise status includes a heart rate recovery of the user and a respiratory rate recovery of the user; making an adjustment decision by comparing the first exercise solution and the exercise status by the calculating unit; and modifying the first exercise solution to become a second exercise solution according to the adjustment decision by the calculating unit.